“I’ve been receiving phone calls all day — not just from friends, but colleagues I’ve never met, saying, `He was my mentor’ or `I’ve never met anyone like him,’ ” said a tearful Nemser Crowley, his high school sweetheart and wife since 1980. “It shows what a wonderful, brilliant man he was, with absolute integrity.”

Crowley’s wife and daughter were with him when he passed away Saturday night at North Shore University Hospital in Manhasset.

He was diagnosed with cancer about six months ago. Doctors told Crowley that he was in remission, but his weakened state left him vulnerable to a recent illness, loved ones said.

When he wasn’t wearing out shoe leather for The Post working on sensational stories such as the Ted Ammon murder and Gilgo Beach serial killer, Crowley was a prolific author of true-crime and mystery-thriller novels.

His works included “Almost Paradise,” about Ammon’s death, and “Hack,” a novel about a New York tabloid columnist. Other works included “Sleep My Little Dead: The True Story of the Zodiac Killer,” “Burned Alive” and “The Surgeon’s Wife.”

His latest work, “Shoot,” is scheduled to be released in October by his publisher, Titan Books.

He was named Journalist of the Year in 2014 by the Press Club of Long Island.

Crowley studied acting and writing at Adelphi University and Queens College. He dabbled in acting, loved ones said, and even appeared in the 1971 play “Playboy of Seville,” which starred Meryl Streep and Michael Moriarty.

Crowley worked for The Post for 36 years before retiring in 2013. He would have turned 67 on April 29.